1. Field of the Invention
The present invention relates, in general, to wafer fabrication systems.
2. Description of the Related Art
The production of semiconductor devices consists of many layers of chemical compounds applied to or removed from a silicon base. The base is a disk known as a xe2x80x9cwaferxe2x80x9d. Depending on wafer size and chip complexity, each wafer can contain 25 to several hundred separate identical chips.
Using photolithography, the pattern of electrical circuits for a given layer is captured on the wafer. The image is developed, and the wafer moves to another process, either adding or modifying a layer, or etching it out in the pattern of the lithographic image. This process is repeated many many times in many layers to get a full 3-D electronic circuit. The dimensions of these circuits are incredibly tiny. Present technology is in the range of 0.25 micron line width or feature size.
Wafer fabrication systems are utilized to manufacture semiconductor devices. A wafer fabrication system can be conceived of as being composed of production equipment and utility systems. Production equipment can be conceived of as being composed of functional units known in the art as xe2x80x9cproduction tools.xe2x80x9d Utility systems can be conceived of as being composed of functional units known in the art as xe2x80x9citems of utility system equipment.xe2x80x9d
Prior to the initial installation of a wafer fabrication system, the production equipment and utility systems are individually designed and integrated together using top down engineering design techniques in order to yield the wafer fabrication system. Each individual production equipment and utility system design, as well as the overall wafer fabrication system design, is typically recorded in its own equipment layout plan drawing.
Subsequent to the initial installation of a wafer fabrication system, it is common within the industry to take a xe2x80x9cmodularxe2x80x9d approach to the production equipment and utility systems making up the wafer fabrication system. That is, the constituent parts of the production equipment and the utility systems are treated as functional members that can be independently added, modified, replaced, relocated, removed, or upgraded with only concern for impacts local to the modification, replacement, relocation, removal, or upgrade.
With respect to the manufacture of semiconductor devices, there are hundreds of different production tools utilized to apply or remove or condition the various layers within the semiconductor device. Additionally, there are dozens of different chemicals required to produce the desired effects. The different chemicals require separate distribution, or utility, systems to deliver them.
Use of the modular approach to production equipment and utility systems allows the piecemeal addition, modification, replacement, relocation, removal, and/or upgrading of production tools making up the production equipment and items of utility equipment making up the utility systems as new process steps become necessary, or when production tools are improved. In practice, there are many advantages to the modular approach. One advantage is that the modular approach is highly efficient and effectively allows an existing wafer fabrication system to continuously evolve over time in order to meet expanding demand and changing manufacturing procedures. In a sense, a wafer fabrication system resulting from the modular approach is the best system possible in that it is uniquely adapted to the needs at hand, a fact which arises from its evolutionary growth in response to a changing environment of present and future needs.
One significant disadvantage to a wafer fabrication system utilizing the modular approach is that its evolutionary growth pattern means that there is no overall conscious design, or plan, applicable to the wafer fabrication system which has been evolving for any significant length of time. In theory, this disadvantage could be overcome by maintaining extensive documentation about the wafer fabrication system as it evolved. In practice, this has not happened.
The semiconductor device manufacturing industry has been in the midst of sustained capacity expansion for years. To keep up with demand, companies have been installing and updating production equipment and items of utility system equipment on a need-driven basis. Consequently, many of today""s semiconductor device wafer fabrication systems consist of a bewildering array of production tools and items of utility system equipment assembled together in response to past needs. While such wafer fabrication systems do work exceptionally well, they give rise to significant difficulties from the standpoint of facilities engineers attempting to manage, maintain, or upgrade such wafer fabrication systems.
One such difficulty arises from the lack of documentation, and consequent lack of understanding, concerning the interrelationships of the production tools composing the production equipment. Another difficulty arises from the lack of documentation, and consequent lack understanding, concerning the interrelationships of the items of utility system equipment composing the utility systems. Yet another difficulty arises from lack of documentation, and consequent lack understanding, concerning the interrelationships of the various production tools and items of utility system equipment. This lack of documentation and understanding exists since existing wafer fabrication systems, composed of production equipment made up of various and sundry production tools and utility systems made up of various and sundry items of utility system equipment, are the result of sustained evolution, often over a period of several years, in response to needs that had to be satisfied immediately (e.g., either to avoid a shutdown of the facility or to quickly ramp up for production of a new product or quantity of product).
The result of the foregoing described process or real-time installation and modification is a highly evolved sprawl of well-functioning production equipment which is often partially undocumented (that is, because of the rapid modification without documentation, the original equipment layout plan drawings quickly become inaccurate representations of the production equipment and utility systems making up a wafer fabrication system). That is, since the production tools (and their supporting items of utility system equipment) had to be installed and/or modified virtually in real time, time for documenting such installations/modifications did not typically exist at the time of such installations/modifications. Furthermore, rapid growth in the industry has also typically meant that one real-time project has followed on the heels of a preceding real-time project. Consequently, often, time is not available to go back and document the changes in production tools and their supporting distribution systems which gave rise to existing production equipment. Thus, existing wafer fabrication systems are in the main vastly undocumented. This lack of documentation gives rise to a corresponding lack of information regarding the overall system functioning.
Incomplete documentation and overall wafer fabrication system understanding poses several grave difficulties to facilities engineers due to the overwhelming complexity of existing systems. The following example of an existing system will help to demonstrate a few of the difficulties arising from such complexity and lack of documentation.
At the NEC Electronics, Inc. semiconductor device manufacturing facility in Roseville, Calif., there are literally hundreds of production tools in place, which, as discussed above, collectively make up the production equipment. A great number of the relationships and interrelationships of the production tools in place are poorly documented or undocumented for the reasons set forth above. In addition, connected to the production tools in place are the following utilities, many of which have relationships and interrelationships that are likewise undocumented. Thirty-five (35) bulk liquid chemical supply or return systems. These chemical supply and return system carry various types of chemical ranging from IPA to MEK to HF to H2SO4 and many others. Four (4) different types of electrical power systems, all at various voltages. Five (5) different types of communication systems. Eleven (11) bulk gas systems. These bulk gas systems carry various types of chemical including Argon, Nitrogen, Hydrogen, Oxygen, compressed air, etc. Forty (40) bottled gas systems (serving only 1-5 tools). These bottled gas systems include several types of gases such as freons, CO2, HBr, Nexe2x80x94Krxe2x80x94F, PH3, SF6, etc. Four (4) major process exhaust systems: acid exhaust, alkali exhaust, organic exhaust, powder exhaust. (Each has several scrubbers to release only cleaned air to the atmosphere.) Several (e.g., house and process) vacuum systems. Six (6) wastewater systems for different chemical mixtures. Five (5) water systems: Cooling supply and return, super high purity (deionized or DI) water, hot DI water, industrial water.
Those skilled in the art will recognize that each of the foregoing described utility systems contains utility system equipment such as mains, valves, panelboards, branches, plus all sorts of generation equipment, pumps, tanks, pressure reducing stations, etc. Those skilled in the art will further realize that the number of utilities serving the production equipment fluctuates constantly, as the mix of different tools evolves and changes. Those skilled in the art will yet further realize that it is common for as many as 20 of the foregoing described utility systems to come together at a single production tool, depending upon the necessary requirements (e.g., chemical, vacuum, power, and cooling requirements) of the production tool.
As noted above, the modular approach to wafer fabrication systems allows the addition, modification, replacement, relocation, removal, and/or upgrading of individual production tools and items of utility equipment. Unfortunately, the addition, modification, replacement, relocation, removal, and/or upgrading of such production tools and items of utility equipment is generally not just a simple matter of stopping the wafer fabrication system, plugging in the new production tool or item of utility equipment, and re-starting the system. Insofar as production tools are typically being served by a number of different utilities, and insofar as the production tools are themselves often serving as conduits for utilities to other production tools, the addition, modification, replacement, relocation, removal, and/or upgrading of production tools or items of utility system equipment often requires that the production tools and/or utilities surrounding the production tool(s) or item(s) to be replaced or modified be taken off line.
More often than not, the addition, modification, replacement, relocation, removal, and/or upgrading of production tools or items of utility system equipment requires extensive engineering modification of existing production tools and utility systems, such as retrofitting connections, adjusting power supplies, modifying software controls, etc. in order to make the added, modified, replaced, relocated, removed, and/or upgraded production tools or items of utility system equipment function effectively. This operation of xe2x80x9cintegratingxe2x80x9d a new production tool into existing production equipment is known in the art by the term xe2x80x9chook-upxe2x80x9d. Those skilled in the art will recognize that there are always unforeseen difficulties which arise during hook-up. These difficulties need to be overcome in order to for the new production tool or items of utility system equipment to function effectively. Overcoming these difficulties takes time, and can sometimes take a great deal of time.
Insofar as adding, modifying, replacing, relocating, removing, and/or upgrading production tools or items of utility system equipment can require that all or part of a wafer fabrication system be shut down, it is extremely important that the facility engineers deciding whether or not to deploy new production tools or items of utility system equipment be able to estimate the worst case scenarios in order to determine a plan of installation having substantially no effects on the wafer fabrication system operation. This means that they need to be able to estimate the effect on the wafer fabrication system of taking off-line the production tools or items of utility system equipment necessary to effect the change/modification. Unfortunately, assessing such worse case scenarios is not something easily done in the art due to the lack of documentation and understanding regarding the interrelationships of the production tools and their supporting utilities within the evolved existing wafer fabrication systems.
Since in the art there is typically no adequate description of the interrelationships within the evolved system, it is very difficult for facility engineers to anticipate the effects of proposed changes to production equipment or utility systems. That is, if the relationships are not well documented, it is very difficult to anticipate the effect of, say, shutting off a valve delivering sulfuric acid to a tool, especially if that valve serves several conduits or the tool itself serves several other tools. Since the interrelationships between components of the production equipment, the interrelationships between components of the utilities serving the production equipment, and the interrelationships between the components of the production equipment and the components of the utilities may not be generally well known or documented, shutting down parts of the system often has many unexpected effects. Those skilled in the art will recognize that this lack of knowledge is undesirable, and makes an already risky operation more risky. In the absence of the present invention, the common approach to the foregoing noted difficulties is for each utility to be separately (which are usually outdated, for the reasons set forth above) documented on a large blueprint drawing (or drawings) of its own. To examine all the utilities at a given production tool, many drawings must be researched (typically at least one drawing per each utility).
Those skilled in the art will recognize that, for a proposed addition to or modification of a group of tools (such modifications tend to come in groups needed to support a certain product and defined quantity of the product), facilities construction engineers, utilizing the existing (and typically outmoded) blueprint drawings on a piecemeal basis, prepare a utility matrixxe2x80x94a listing of the utility demands for the entire group of production tools to be modified. Thereafter, the construction engineers evaluate the matrix to determine if utility service is adequate in the proposed locations, or whether system upgrades will be required. If system upgrades will be required, the type and cost of the upgrade are determined.
As product planners attempt to refine their production mix, several such proposed modifications occur throughout the year. Thus, from a planning standpoint the foregoing described procedure is very labor intensive and fraught with risk. Notwithstanding the foregoing, that risk becomes real and the dangers present when a design decision is made and the changes actually implemented.
Those skilled in the art will recognize that, even if the evolutionary nature of the system had been well documented, from a practicable standpoint it is extremely difficult to represent all the hook-up information related to installing or modifying production tool(s) as a drawing single. In most practical instances, there are just too many branch lines feeding any one production tool. With hundreds of tools and dozens of utilities interlinked, such a diagram would be a very convoluted web, virtually impossible to draw even if it could be understood.
Those skilled in the art will also recognize that even if the evolutionary nature of the production equipment and utility systems making up the wafer fabrication system had been well documented, from a practicable standpoint it is extremely difficult to represent wafer fabrication system-wide impacts related to installing or modifying production tool(s) and/or utility systems. The practical reasons for this is that most wafer fabrication systems maintain separate blueprint drawings for separate production tools and utility systems, which makes an overall wafer fabrication system assessment of likely impacts substantially impracticable.
It is therefore apparent that a need exists in the art for a method and system which can dynamically learn, coordinate, and present the massive amount of production tool and utility interconnect data from existing and evolving wafer fabrication systems, and present such learned information in such a fashion that the costs, benefits, and impacts of any proposed modifications of production equipment and/or utilities on parts of the wafer fabrication system can be adequately accessed.
A method and system have been invented which can dynamically learn, coordinate, and present the massive amount of production tool and utility interconnect data from existing and evolving wafer fabrication systems. The method and system capture an evolving wafer fabrication system by mapping at least one interaction between a selected at least one integral part associated with the wafer fabrication system and at least one other integral part associated with the wafer fabrication system.
The foregoing is a summary and thus contains, by necessity, simplifications, generalizations and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the present invention, as defined solely by the claims, will become apparent in the non-limiting detailed description set forth below.